Opening up lath and plaster, need to tear it all down?

So I'm purchasing a home that has some water damage from a previously leaking roof. In the bedroom there are stains in the ceiling and wall from this leak, and the inspector recommended opening it up and making sure the wood isn't rotting. The plywood under the linoleum floor was so damaged that it likely needs to be pulled up and replaced too, so I suspect a decent amount of water leaked in.

Since the house was built in 1917, I'm sure it's got lath and plaster walls. My question is, if I do take plaster off the wall, and pull lath off, once (and if) it looks good to close back up, what do I need to do? Do I try and install drywall in a neat hole that I cut open? Or do I need to tear down the whole wall and put drywall up?

Also, what should I expect to find behind that wall? Insulation? Anything? It's an exterior wall.

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Opening up lath and plaster, need to tear it all down?

I have worked on a number of older homes in my area, having to cut holes into plaster/lath walls. I have used drywall to make repairs but I add some backing to the area where the drywall will go. I have even had to enlarge the opening to get wood into the area so I have something to attach the drywall to. Once attached, finish it out as ususal-although a bit more work there, repaint and all should be well. David

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Opening up lath and plaster, need to tear it all down?

From my experiences working with antique homes, removing the plaster is quite a messy job. Be sure to wear a mask as it is very dusty. The plaster is held to the wall with lath. Lath is wooden strips nailed to the studs with a small space between the lath. The plaster is applied to the lath and most times the plaster had horse hair as a reinforcement.

There was never insulation in the walls unless it was added at a later time. If you have to remove the plaster and install drywall there is a chance the studs are not the same dimension so be prepared to make adjustments there, just in case. While you have the walls open it would be a good time to update the electrical.

Opening up lath and plaster, need to tear it all down?

Plaster walls do not mix well with water. It will take about seven years for the plaster to dry out if it has gotten any significant amount of water in it. If the plaster got wet from the leaking roof, it needs to come out. That's from very recent experience.

Also, from recent experience...unless someone blew insulation in from the outside, you are not likely to find any behind those plaster walls. Also, your exterior walls are most likely to be 2x4 (a full 2x4, not 1.5x3.5) and the interior walls should be 2x3, not including the lathe.